John Milton's Paradise Regained is typically contextualized within the politics of the Restoration; this article, however, argues that his 1671 poem recapitulates his antiliturgical arguments of the 1640s. Juxtaposing Milton's antiliturgical pamphlets, Eikon Basilike, and Eikonoklastes, I show the common interest in the language of “constancy” amid the debate over the use of the Book of Common Prayer. This language resurfaces in Paradise Regained, where the “constant” Son belatedly counters Eikon's cooption of constancy in the prayer book debates. The Son's famously interior, inward understanding of faith—expressed as neostoic “constancy”—rebuts arguments for the use of external forms of liturgy, rehearsing language and imagery from Milton's 1640s prose. Milton consequently emerges as a figure both retrograde and innovative, using old arguments and royalists' own terms in an unprecedented generic context to assert his defiance against the restoration of the English liturgy.